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Polyoxometalate catalyzed ozonation of chemical pulps in organic solvent media
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Orientador(es)
Resumo(s)
Polyoxometalate (POM) catalyzed ozonation of chemical pulps in organic solvent media was found to
be particularly effective and selective environmentally benign bleaching approach providing a way for
substantial increase in pulp brightness, viscosity and degree of delignification in comparison with other
ozone-based bleaching techniques. A series of tested low-boiling polar aprotic and protic organic solvents
showed awell-defined capacity for ozonation improvement in the presence of Keggin-type heteropolyanion
[PMo7V5O40]8− (HPA-5). Even moderate solvent proportion of 6% (w/w) in the reaction solution caused
additional gain in brightness up to 3.4% ISO with simultaneous increase in pulp viscosity up to 8.8% and
lignin removal up to 18.9% after HPA-5 catalyzed ozonation (0.8% O3; 0.5mMHPA), as compared with the
control solvent-free process. An aqueous acetone solutionwas found to be the preferred reaction medium
in terms of pulp brightening and delignification. Under optimized conditions, the POM-catalyzed ozonation
of eucalypt kraft pulp in acetone/water solution showed remarkable brightness improvement by
15.1% ISO with additional lignin removal by 39.4% and increase in intrinsic viscosity by 3% in comparison
with pulp bleached in water media
Descrição
Palavras-chave
polyoxometalate heteropolyanion ozone ozone bleaching organic solvent eucalypt kraft pulp
Contexto Educativo
Citação
"Chemical Engineering Journal". ISSN 1385-8947. 155 (2009) 380-387
Editora
Elsevier